1. Field of the Invention
The present invention relates to a relaying apparatus, and in particular to a relaying apparatus comprising input side accommodating portions including input side queues, a plurality of output side accommodating portions respectively including output side queues, and a switch fabric for mutually connecting the input side queues and the output side queues in a mesh form.
A relaying apparatus such as a router accommodating a plurality of networks and relaying packets between the networks receives the packet from the input side network, determines the output side network for the packet, and performs routing for the transmission of the packet to the determined network.
In such a relaying apparatus, it is possible that the packets are simultaneously transmitted to a single output side network from a plurality of input side networks. Thus, the issue of the competition of scrambling for the output side network occurs. This issue can be solved by temporarily queuing the packets. However, what kind of queuing method should be adopted is important for the performance of the relaying apparatus.
2. Description of the Related Art
FIG. 10 shows an arrangement of a general relaying apparatus. This relaying apparatus is composed of an input side accommodating portion 10 for determining output destinations of packets 61_1-61_N (hereinafter, sometimes generally represented by reference numeral 61) inputted from the network, a switch fabric 40 for transferring packets 62_1-62_N (hereinafter, sometimes generally represented by reference numeral 62) received from the input side accommodating portion 10 to predetermined output destinations, and an output side accommodating portion 50 for outputting packets 63_1-63_N (hereinafter, sometimes generally represented by reference numeral 63) received from the switch fabric 40.
The input side accommodating portion 10 is composed of input side accommodating portions 10_1-10_N having the same arrangement, and the output side accommodating portion 50 is composed of output side accommodating portions 50_1-50_N having the same arrangement.
The input side accommodating portions 10_1-10_N and the output side accommodating portions 50_1-50_N are logically connected by the switch fabric 40 in a full mesh form. Thus, the relaying apparatus transfers the packets inputted to the input side accommodating portions 10_1-10_N to the predetermined output side accommodating portions 50_1-50_N based on transfer information thereby realizing the packet relay between different networks.
Accordingly, a physical link 62_1, wherein the same reference numeral as the packet 62_1 is used in FIG. 10, the other physical links 62_2-62_N are likewise applied, and hereinafter, these reference numerals 62_1-62_N are sometimes generally represented by reference numeral 62, connecting the input side accommodating portion 10_1 and the switch fabric 40, for example, is multiplexed with logical links connecting the input side accommodating portion 10_1 and the output side accommodating portions 50_1-50_N. The same may also apply to the physical links 62_2-62_N.
Also, physical links 63_1-63_N, wherein the same reference numerals as the packets 63_1-63_N are used in FIG. 10, connecting the switch fabric 40 and the output side accommodating portions 50_1-50_N are multiplexed with logical links connecting the output side accommodating portions 50_1-50_N and the input side accommodating portions 10_1-10_N.
As mentioned above, the relaying apparatus performs a queuing of the packets addressed to the same output side network, and the queuing is classified into three categories according to a physical location of a buffer (queue); the location of the output side queue (buffer) resides in the input side accommodating portion 10, in the switch fabric 40, or in the output side accommodating portion 50.